Differential gear unit

Abstract

Arranged within a differential gear case are first and second side gears rotating together with first and second output shafts, respectively; first and second differential gears engaged with one of the first and second side gears and rotatably supported within cylindrical holes, respectively, so as to be partially engaged with each other to move circularly together with the differential gear case; and a viscous coupling capable of transmitting, between a hub rotating together with the output shaft and a housing, a torque in response to the difference in the speed. The outer periphery of the housing is provided with a cam surface to be engaged, in the direction of rotation, with the first and second differential gears to press and bias the first and second differential gears against the inner cylindrical surfaces of the cylindrical holes.

What is claimed is: 
     
       1. A differential gear unit comprising: a differential gear case rotationally driven on an axis of coaxially extending first and second output shafts;   first and second driven gears rotatably received in said differential gear case in such a manner as to be coaxial with said axis said first and second driven gears being rotated integrally with said first and second output shafts respectively;   first and second differential gears adapted to engage with one of said first and second driven gears and rotatably supported within an accommodation section of said differential gear case so as to be partially engaged with each other, said first and second differential gears being circularly movable integrally with said differential gear case;   a first transmission member rotatably received in said differential gear case in such a manner as to be coaxial with said axis said first transmission member having an outer periphery provided with cam means engaged, in the direction of rotation, with said first and second differential gears, said cam means for pressing and biasing said first and second differential gears against an inner wall surface of said accommodation section; and   a second transmission member being rotated integrally with said second output shaft and arranged relatively rotatably with respect to said first transmission member with an interposition of limited slip differential means for transmitting a torque in response to a difference in a rotational speed.   
     
     
       2. A differential gear unit according to claim 1, in which said cam means provided on said outer cylindrical surface of said first transmission member comprises a pair of grooves extending in a direction of the axis. 
     
     
       3. A differential gear unit according to claim 1, in which said limited slip differential means comprises: an annular housing having a substantially U-shaped longitudinal half section and acting as said first transmission member;   a cylindrical hub arranged relatively rotatably with respect to said housing and acting as said second transmission member;   an annular operative chamber defined by said annular housing and said cylindrical hub;   a plurality of outer plates accommodated in said annular operative chamber, said outer plates being in spline engagement with an inner periphery of said housing and being spaced equally by spacer rings;   a plurality of inner plates accommodated within said annular operative chamber, said inner plates being individually sandwiched by said outer plates and being in spline engagement with an outer periphery of said hub in such a manner that said inner plates are slidably movable in said direction of the axis; and   a viscous fluid filled within said operative chamber.   
     
     
       4. A differential gear unit comprising: a differential gear case rotationally driven on an axis of coaxially extending first and second output shafts;   first and second driven gears rotatably received in said differential gear case in such a manner as to be coaxial with said axis, said first and second driven gears being rotated integrally with said first and second output shafts, respectively;   first and second differential gears adapted to engage with one of said first and second driven gears and rotatably supported within an accommodation section of said differential gear case so as to be partially engaged with each other, said first and second differential gears being circularly movable integrally with said differential gear case;   a differential slip limiting means arranged within an interior of said differential gear case for inducing a differential slip limiting torque to press and bias said first and second differential gears against said differential gear case when a gripping force of drive wheel connected to one of said first and second output shafts with respect to a road surface has thoroughly resulted in zero;   said differential slip limiting means comprises, a first transmission member rotatably received in said differential gear case in such a manner as to be coaxial with said axis, said first transmission member having an outer periphery provided with cam means engaged, in the direction of rotation, with said first and second differential gears, said cam means for pressing and biasing said first and second differential gears against an inner wall surface of said accommodation section; and   a second transmission member rotated integrally with said second output shaft and arranged relatively rotatably with respect to said first transmission member for transmitting a torque in response to a difference in a rotational speed.   
     
     
       5. A differential gear unit according to claim 4, in which said differential slip limiting means comprises: an annular housing having a substantially U-shaped longitudinal half section and acting as said first transmission member;   a cylindrical hub arranged relatively rotatably with respect to said housing and acting as said second transmission member;   an annular operative chamber defined by said annular housing and said cylindrical hub;   a plurality of outer plates accommodated in said annular operative chamber, said outer plates being in spline engagement with an inner periphery of said housing and being spaced equally by spacer rings;   a plurality of inner plates accommodated within said annular operative chamber, said inner plates being individually sandwiched by said outer plates and being in spline engagement with an outer periphery of said hub in such a manner that said inner plates are slidably movable in said direction of the axis; and   a viscous fluid filled within said operative chamber.